In dishwashers, conventionally, there has been a technique of supplying a detergent to wash water based on a detection value of a sensor. For example, in a dishwasher disclosed in Patent Document 1, a detergent concentration in wash water is measured by measuring conductivity between a pair of electrodes immersed in the wash water. Further, the detergent is to be supplied into the wash water such that the detergent concentration in the wash water is constant.
Moreover, in a dishwasher disclosed in Patent Document 2, there is provided a glassy cell plate in a conduit line in which wash water flows, and a light-emitting diode and a photodiode are disposed with the cell plate sandwiched. Furthermore, light emitted from the light-emitting diode is detected by the photodiode, whereby turbidity of the wash water is measured.
[Patent Document 1] Japanese Patent Application Laid-open No. 2001-139099
[Patent Document 2] Japanese Patent Application Laid-open No. 2003-225191